Simple Past tense:
Shows an action done in the past without any further details.
Examples :
Sarun played in the park yesterday.
He did his homework yesterday.
Simple Present tense:
Shows an action that happens now without any further details.
Examples:
Sarun plays in the park.
He does his homework.
Simple Future tense:
Shows an action that will happen in the future without any further details.
Examples:
Pooja will sing a song.
She will be teaching Physics.